ppt

PROTECTING GROUNDWATER
INSTEAD OF MITIGATING MISTAKES
MME Workshop
Marshall 2014
Bruce Olsen
WHY PROTECT GROUNDWATER?
•
•
•
•
•
•
Principal Source of Drinking Water in MN
Recharges Many Lakes and Streams
Extensively Used to Irrigate Crops
Supports Habitat for Many Plants and Animals
Heavily Used for Industry in Some Places
More Dependable Water Supply Than Surface
Water
WHAT ARE THE PROBLEMS?
• Over Use – Pumping More Than is Replaced
• Misuse (Wasting) – Pumping for a Less Important
Need
• Contamination – Introducing a Substance that
Makes Groundwater Unusable for Others
• Knowledge Gap – Detailed Information About the
Resource is Lacking in Many Areas
• User Awareness – Limited Understanding of
Cause and Effect
WHERE MINNESOTANS GO FOR A
DRINK OF WATER
• Approximately 4,000,000 Obtain Their
Drinking Water from a Public Water Supply
– 1,000,000 From Surface Water
– 3,000,000 From Wells
• 1,350,000 Obtain Their Drinking Water
from a Private Well
PUBLIC WATER SUPPLY SYSTEMS
• Community Systems
970
• Nontransient Systems
657
• Transient Systems
6,977
8,604 Total
LAND OF 10,000 LAKES & PUBLIC WATER
SUPPLY WELLS
There Are As
Many Public
Water Supply
Wells As There
Are Lakes In
Minnesota
RESIDENTIAL WELLS
• Approximately 1,350,000 Minnesotans Use
Private Wells
• Well Drilling Began Late 1800’s
• State Construction Regulations in 1975
• No State or Federal Monitoring
• Generally, 20% Show Nitrate Contamination
• Generally, 5% Show Bacterial Contamination
COUNTY WELL INDEX
•
•
•
•
•
•
Web Site for Retrieving Well Records
Public Water Supply Wells Not Shown
Operated by MGS and MDH
Mapping Service Linked to Records
Contains Approximately 450,000 Records
Principle Source of Subsurface Data for
Minnesota
PUMPING PROBLEMS
• Impacts on Surface Water – White Bear Lake
(city pumping), Straight River (irrigation),
Savage Fen (city pumping)
• Impacts on Groundwater – Granite Falls
(ethanol plant), Brooten-Belgrade Area
(irrigation), Downtown MPLS-STP (air
conditioning)
CONTROLLING PUMPING
• DNR Regulates Wells that Pump 10,000
gallons/day or 1,000,000 gallons/year
• 11,742 Active Appropriations Permits
• Pumping Categories for 2011
– Public Water Supply
– Industrial Processing
– Irrigation
– Other
199 billion gal/year
103
73
72
447 billion gal/year
CONVERSION EXERCISE
If an acre foot (1 foot of water deep over an acre) =
325,853 gallons
How many acre feet are in 447 billion gallons?
1,371,784 acre feet
If the area of Lyon County is 461,734 acres, how
many feet of water could be applied in 447 billion
gallons?
2.97 feet over the entire county
214.34 feet over the city of Marshall (6,400 acres)
UNDERSTANDING THE CONTAINER
• A Geologic Model is Key to Estimating the
Available Quantity of Groundwater
• Geologic Materials Affect the Directions and
Rates of Groundwater Flow and Water Quality
• Geologic Conditions Affect Well Construction
and Operating Costs
• Understanding Geologic Conditions Affects the
Accuracy of Computer Models & GW
Management
MAYONAISE JAR AQUIFER
LESSON 1
• Help the Student Understand
– How groundwater is stored in a gravel or sand
aquifer
– How differences in geologic materials impact the
amount of available groundwater
• Uses inexpensive and readily available
materials
• Discussion Items for the Instructor
LESSON 1
COUNTY-LEVEL GROUNDWATER
CONDITIONS & ISSUES
• Dakota County is Located in the SE Part of the
Twin Cities Area
• Groundwater is the Principle Source of
Drinking Water
• Mixed Urban and Rural Setting
• Rapidly Expanding Population in the Previous
20 Years
• Groundwater Quantity and Quality Concerns
Ground Water Appropriations
Permits for Wells that
Pump 10,000 Gallons/Day or
1,000,000 Gallons/Year
Glacial Wells Versus
Depth to Bedrock
51 – 100 Feet
0 – 50 Feet
Bedrock Geology
Aquifer Materials
Comprise the Uppermost
Bedrock Throughout
Most of the County
Source – Metropolitan Council
Prairie Du Chien – Jordan Aquifer
Hydraulic Head (Feet MSL)
Not Present
Geologically Sensitive
Tritium Levels
Prairie du Chien - Jordan
Post-1953 Recharge
Pre-1953 Recharge
Water Table Vulnerability
1 = Lowest
2
3
4 = Highest
Nitrate Levels in
Public Water Supply Wells
> 10 ppm
> 1 < 10 ppm
< 1 ppm
Potential Contamination Sources
Referenced to Water Table
Vulnerability
Leaking Tank Site
Permitted Feedlot
FILLING THE KNOWLEDGE GAP
• Upgrading the County Well Index (MGS,MDH)
• Expanding the County Geologic Atlas Program
(MGS,DNR)
• Expanding Water Level Monitoring Program
(DNR, County Cooperators, USGS)
• Expanding Characterization of Groundwater
Chemistry (DNR, MPCA, MDH, MDA)
• Improving Web Access to Agency Data
WELL………………
• A Well is “an excavation that is drilled, cored,
bored, washed, driven, dug, jetted, or
otherwise constructed if the excavation is
intended for the location, diversion, artificial
recharge, or acquisition of groundwater.”
• A Tube that is Constructed From the Land
Surface to a Source of Groundwater.
MAYONAISE JAR AQUIFER
LESSON 2
• Help the Student Understand
– How a water supply well works
– How the rate of groundwater recharge affects the
quantity of available groundwater
• Builds on the Concepts Introduced in Lesson 1
• Discussion Items for the Instructor
LESSON 2
PROBLEMS WITH OLDER WELLS
• Many Pre-1975 Wells Do Not Meet Current
Construction Standards and
– May be susceptible to pathogen or other
contamination sources
– May provide pathways for contaminants to move
deeper
• Unused Wells Must Be Sealed
• Sealing May be Very Costly ($100,000 or more for
Large Diameter Wells)
• > 250,000 Wells Have Been Sealed in MN
Lakefield Example
• Unsealed Old City Wells Presented a Threat to
Existing and Planned City Wells
• High Levels of Diesel Fuel Contamination in a
Near-Surface Sand Surrounding City Wells
• High Degree of Hydraulic Separation Between
Upper Sand and Deeper Aquifer
• Limited Geographic Extent to the Deeper
Aquifer
Lakefield City Wells
Circa 2002
Current Wells
Former Wells No Longer
Used
LAKEFIELD CITY WELL #2
Near Surface Aquifer
Contaminated With Diesel
Fuel from the Former City
Power Plant.
Two Operational and Three
Unsealed Former City
Wells Presented a
Contamination Pathway
Risk to the Aquifer.
Well 2 - RUSTED LINER PIPE
Hole in Casing
SEALED BUT NOT FORGOTTEN
4 Wells Sealed
All Within 100 Feet of
Each Other
“Petro-Fund” Paid for 3 of
Them
City Had Unforeseen
Expense Sealing the Other
CONTAMINATION
• Human-Made or Naturally Occurring
Substances
– Biological (bacteria and viruses)
– Chemical Contaminants (60,000+ Chemicals)
– Change the Natural Chemistry of Groundwater by
Mixing (Multi-aquifer Wells, Storage/Retrieval)
• Generally, Analytical Methods Lag Behind
Concerns
Human Health Impacts
• Gauge Used to Assess Extent of
Contamination or Set a Remediation Goal
• Maximum Contaminant Level (90 Federal)
• Health Risk Limit (Minnesota)
• EPA or State Approved Analytical Methods
• Setting Levels is a Time Consuming Process
QUESTION –
CAN YOU SEE GROUNDWATER
CONTAMINATION?
NOT VERY OFTEN
WHAT IS THE MOST COMMONLY
DETECTED GW CONTAMINANT?
Nitrate Nitrogen
Potential Sources –
• Septic Systems and Leaking Sewer Lines
• Feedlots
• Fertilizer Storage and Use
• Stormwater Management
• Infiltrating Surface Runoff
Geologic Sensitivity of the Water Table
ASSUMPTION:
Red Colored Areas Should
Show Areas Where the Water
Table Is Most Likely To Be
Impacted By Nitrate Sources.
Nitrate Detections Versus Water Table Sensitivity
Data Sets –
7,194 of 63,164 CWI Records
1,336 of 17,291 PWS Sources
Assessing Contaminant Levels
• Informal (County-level Well Testing, Nitrate
Clinics, County Geologic Atlas, USGS studies,
Research by Academia, Real Estate
Transactions, Legislative Initiative)
• Regulatory (Well Construction, Remediation
Programs, Permitting Programs, Public Water
Supply Program, Nitrate Monitoring Network,
MCL-HRL Development)
ADDRESSING CONTAMINATION
•
•
•
•
•
Assessment (Initial and Long-term)
Regulatory Clean Up
Voluntary Clean Up
Adding Treatment to Existing Water Systems
Replacing Wells (Replacement or Alternate
Supply)
• Reducing Pumping – Adding Other Sources
MAYONAISSE JAR AQUFIER
LESSON 3
• Help the Student Understand
– The water table
– How pumping can move contamination deeper
into an aquifer
• Builds on the Concepts Introduced in Lessons
1&2
• Discussion Items for the Instructor
LESSON 3
CONTAMINATION IS EXPENSIVE
• Replacing a Contaminated Well
– $30,000 to $500,000 for a community well
– $5,000 to $15,000 for a private well
– $5,000 or more to hook up to a community supply
• Adding and Maintaining Treatment
– $150,000 to > $10 million for a city
– $1,000 to > $5,000 for a home owner
EXAMPLES OF CLEAN UP COSTS
• Nationally, EPA Spent $40 billion on Superfund
since 1986 ($243 Million Annual Budget Now)
• Minnesota
– Closed Landfill program (109 sites)
• $41,117,309 for reimbursements since 1986
• $16,847,085 in 2013 for administration
– Petroleum Remediation
• $40 milion in Petrofund reimbursements since 1987
• Clean up for Contaminated GW is typically $100,000 $1million per site (EPA)
DEEPER AQUIFERS HAVE OTHER
EXPENSIVE PROBLEMS
• Limited Geographic Extent or Varying Geology
– Test Drilling and Test Pumping
– Extend Water Lines to New Well(s)
• Different Chemistry Requiring Treatment
– Iron and Manganese
– Arsenic or Radium
– More Corrosive than Shallow Aquifer Water
• State Regulations May Limit or Prohibit Their
Use
PREVENTING CONTAMINATION
USING REGULATIONS
• Regulatory Programs – (Wells, Fuel & Chemical
Storage Tanks, Feedlots, Aggregate Mining, Solid
Waste Handling & Disposal, Hazardous Waste
Handling & Disposal, Pipelines, etc.)
• Some Programs Omit Smaller Sizes
• Pre-existing Sources may be “Grandfathered In”
• Some Contaminant Sources May Not be Formally
Included
• New Contaminants of Concern May Mean
Unregulated Sources
PREVENTION NON-REGULATORY APPROACHES
• Well Owner Education (MDH, County Health
Agencies, USDA )
• County-Level Water Planning (BWSR,
Counties)
• Source Water Protection (MDH, PWS)
• Groundwater Management Areas (DNR, StateLocal Agencies, General Public)
PUBLIC EDUCATION
• Generally, Event Focused Instead of
Curriculum Focused
• Conferences (MRWA, AWWA, MWWA,
MGWA, U of M) Enough acronyms for you?
• Public Places/Events (County Fairs, State Fair,
Museums, Agency Hallways or Lobbies)
• Educator Workshops (MMEW, Drinking Water
Institute)
EDUCATION GAP REGARDING
GROUNDWATER PROTECTION
• No State-wide Strategy for Educating the
General Public About Groundwater Protection
• No Thorough Evaluation of the Effectiveness
of Current or Previous Education Efforts
• No Formal Steering/Advisory Group Tasked
with Defining and Meeting the Public
Education Needs about Protecting
Groundwater
Let’s Start at the Well
Maintain Setback
Distances From
Potential Contamination
Sources Listed in the
State Water Well Code
OK, What’s the Problem?
Well
USUALLY, IT’S MORE SUBTLE
PROTECTING YOUR HOUSE WELL
• Well Owner’s Handbook (MDH Home Page »
Environments and Your Health » Water » Wells»
Well Owner’s Handbook)
• Primer Describing
–
–
–
–
–
–
Groundwater
Well Construction
Water Treatment Contaminants
Well Maintenance
Water Testing
Groundwater
FINDING YOUR WELL RECORD
• Search “County Well Index”
• See if a Well Record Exists (Search “County Well
Index”)
• Is there a layer of clay at least 10 feet thick?
• If not, the aquifer is geologically sensitive
• If your can’t find a well record, consider the aquifer
geologically sensitive
• Test the Water for Nitrate and Coliform Bacteria
(Indicators of Rapid Recharge)
PROTECTING YOUR HOUSE WELL
• Do Not –
– Allow Surface Drainage to Pond Around the Well
– Remove the Well Cap
– Mix Lawn Chemicals Next to the Well
– Park or Wash Vehicles Next to the Well
– Tie the Dog to the Well Casing
– Cover the Well with Soil or Build Over It
• Maintain Setback Distances Listed in the Well
Owner’s Handbook
PROTECTING COMMUNITY OR
SCHOOL WELLS
• Source Water Assessment
• Wellhead Protection Plan
–
–
–
–
–
Identifies Well Capture Area (10 Year Minimum)
Assessment of Well and Aquifer Vulnerability
Inventory of Potential Contamination Sources
Management Strategy (Includes Education Plan)
Contingency Plan
• Inner Wellhead Management Area
– 200 Foot Radius
– Linked to the Sanitary Survey
SOURCE WATER ASSESSMENT
• Provides an Evaluation of Contamination Risk
to Public Water Supply Wells
• Minnesota Department of Health Home Page
» Environments and Your Health» Water»
Drinking Water » Source Water Assessments
• Search by Name or County
MAYONAISE JAR AQUIFER
LESSON 4
• Help the Student Understand the Challenges
of
– Managing potential contamination sources that
may affect a city well
– Preventing contamination in the future
• Based Upon Actual Problems
• Discussion Items for the Instructor
LESSON 4
QUESTIONS